Bodies for motor vehicles are a combination of assembled parts, including parts that make the frame, interior linings, and external sheet metal that make the exterior of the motor vehicle. Cavities or openings may be formed by these parts, which may create pathways for the introduction of noise or pollution into the cabin of the vehicle. Often there is a need to introduce separators or baffles to close these pathways. However, the geometry of the cavities may make the installation of a separator or baffle difficult or impossible. Therefore, an improved separator and method of installing the separator is necessary.